Moves ImmersiveFullscreenController::SetupForTest into test class

ash/wm/immersive_fullscreen_controller.h

Index: ash/wm/immersive_fullscreen_controller.h
diff --git a/ash/wm/immersive_fullscreen_controller.h b/ash/wm/immersive_fullscreen_controller.h
index b39a9245ff9673f8e842bdc3e5b09891dd67158b..859b3fe9ecd8b57e5b7243d306734cb1732a79be 100644
--- a/ash/wm/immersive_fullscreen_controller.h
+++ b/ash/wm/immersive_fullscreen_controller.h
@@ -73,10 +73,6 @@ class ASH_EXPORT ImmersiveFullscreenController
   ImmersiveRevealedLock* GetRevealedLock(AnimateReveal animate_reveal)
       WARN_UNUSED_RESULT;
 
-  // Disables animations and moves the mouse so that it is not over the
-  // top-of-window views for the sake of testing.
-  void SetupForTest();
-
   views::Widget* widget() { return widget_; }
   views::View* top_container() { return top_container_; }